This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-240870, filed Aug. 8, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
This invention relates to a balloon including a balloon for planetary exploration and a commercial hot air balloon.
2. Description of the Related Art
On a planet where an atmosphere exists, it is possible to float a balloon in the atmosphere for a long time to perform a wide range of observations, as in the case of the earth. When a probe transports the balloon to the planet, the gas for the balloon buoyancy should preferably be conveyed to the planet in a liquefied gas rather than in a gas filled in a high-pressure vessel. It is because the liquefied gas state can advantageously reduce the mass and volume of the probe launched into the space. For example, when the planet has atmospheric temperatures which are relatively high at the altitude of the balloon floating, the gas should be selected from those materials that can maintain the liquefied gas state at the ordinary temperatures and can turn into the gas state at the relatively high atmospheric temperature of the planet. Such materials can be very convenient because they can maintain the liquid state during the transport toward the planet and can turn into the gas state during the floating in the planet""s atmosphere. Specifically, a capsule for containing the balloon is designed to release the balloon when the capsule plunges into the atmosphere of the planet, and then the balloon is allowed to fall through the atmosphere while suspending from a parachute. During this short time of falling, the liquefied gas should vaporize sufficiently to expand the balloon.
In the conventional method of vaporizing the liquid for the balloon buoyancy gas within such a short time, a system has been required that comprises a vessel for containing the liquid, a heat exchanger for vaporizing the liquid, and a piping system for connecting these constituent members with the balloon. For this purpose, the heat exchanger needs to have excellent efficiency. However, there is a limit in improving the efficiency of the heat exchanger. Thus, the vaporization of a large amount of liquid within a short time requires a large scale heat exchanger which has a large surface area to be in contact with the atmosphere. As a result, a reduction effect on the mass and volume of the probe, which is derived from transporting the balloon buoyancy gas in a liquid state, is minimized.
An object of the present invention is to provide a balloon which is lighter and smaller.
According to this invention, there is provided a balloon comprising an envelope; wherein the envelope has a multilayered structure comprising a gas-impervious sheet, and a liquid absorbent sheet overlaid on the inner surface of the gas-impervious sheet.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.